The project wants to provide a portable TCP/IP (and later on maybe UDP) socket interface for as many Common Lisp implementations as possible, while keeping the abstraction and portability layer as thin as possible.

Current functionality includes client side streams and server side stream listening sockets. It doesn't have all the features trivial-sockets supports, but does support all of its features on all supported platforms (which trivial-sockets doesn't); see the feature comparison

Release 0.5.0 adds support for udp sockets, fixes lots of bugs since the 0.4.1 release. Additionally, it adds support for Macintosh Common Lisp (versions 5.0 and up).

Due to the fact that the library is based on the sockets interface provided by the implementation, the library is just as portable accross OSes as the supported lisp implementations. (Meaning at least Windows, MacOS X and Linux.)

There's also a trivial-sockets compatibility library trivial-usocket.

Note that the dependency on SPLIT-SEQUENCE as mentioned below is outdated.